XS is only achievable in Hard (for Second Opinion onwards), Special (for New Blood), Specialist (for Trauma Team) or Extreme difficulty. Because there are no difficulty levels in Under the Knife, an S is the top rank possible in any mission, even the X missions.To get an XS, All the special bonuses must be achieved, and the operation bonus, the vital bonus, and the time bonus must be high enough. Cools must be scored wherever they can be scored, and in certain cases the Healing Touch is required to be able to get a good time bonus.

S

Master Surgeon

S is the highest rank in Under the Knife, and the Easy and Medium difficulties on the other three games. To get an S, the player would require all the special bonuses to even be reached, but at times the total score itself would be too low to go to XS.

A

Senior Surgeon

To get an A, most qualifications are met, but not all of them have been achieved. Normally, three out of the four special bonuses have been achieved. On rare occasions, a player can achieve all the special bonuses but not have a high enough score to attain S rank.

B

Specialist

To get a B, no misses must be performed in most operations. Only certain qualifications have been met.

C

Rookie Doctor

To get a C, the player requires to do minimal work. If a C is given, mistakes have been made, the time limit was nearly up, the vitals dropped pretty low, and many other things. If a Challenge operation is failed in New Blood, a C will be instantly given. Before an X mission is completed in Under the Knife, a C will always be given, even before the operation begins.

Pass

In Trauma Team, this rank is achieved in some surgeries by failing the operation and choosing to continue from the point of failure. When this happens, no matter what the score was and what special objectives were completed, this rank will always be given. As no rank is awarded for the Diagnosis and Forensics fields, this rank is the only one achievable.

In Trauma Team, the ranks are not given any subtitle - instead, depending on the part of the story where the operation takes place, a short exchange between the current doctor and surrounding characters will take place, and it will vary depending on the rank achieved by the player.